The terror and excitement of a century of war, displayed in objects ranging from a vivid description by a schoolboy of a Zeppelin crashing 100 feet from the country house where he had been sent for safety, to a Reuters Land-Rover, still with its "Press" signs, which was damaged in a rocket attack in Gaza, will go on display when the Imperial War Museum reopens to the public on Saturday.

The museum has been closed for a £40m rebuild by architects Foster + Partners, with a spectacularly remodelled atrium at its core, dug down to create an extra level, and surrounded by four floors of galleries, with huge objects including a Harrier jet, a Spitfire, and a German V1 flying bomb suspended from the ceiling.

"Each of the objects will give a voice to the people who created them, used them or cared for them and reveal stories not only of destruction, suffering and loss, but also endurance and innovation, duty and devotion, comradeship and love," Diane Lees, the museum's director, said.

Among more than 1,300 objects in the displays – many seen for the first time – there is a Spitting Image puppet of Margaret Thatcher, a suicide bomb vest, a battered suitcase and a drab desk of bent plywood with a blue cushioned bench.

The suitcase was sent ahead by a Jewish couple who failed to get out of Germany in time. They both died in Auschwitz.

The desk and bench are the dock in which the two Libyans accused of the 1988 Lockerbie bombing of Pan Am Flight 103 – which killed all 243 passengers and 16 crew on board and 11 people on the ground – finally appeared on trial 11½ years later, in a specially built courthouse on an old air force base in the Netherlands. The controversy over the trial has never ended: in 2001, Abdelbaset al-Megrahi was sentenced to life imprisonment. However in 2009, suffering from terminal cancer, he was returned to Libya on compassionate grounds, and he died there in 2012.

"In this modern gallery many of the stories continue to this day, so we are displaying them in a very open-ended way," Nigel Steel, the museum's main historian on the project, said. "We have incorporated many contemporary works of art in these sections – artists are very good at raising questions that have not been answered."

The museum actually opened during the first world war in 1917, but found a permanent home in 1936 in what had been the Bethlem mental hospital in Southwark. It has continued to collect ever since, and Steel said the new displays attempted to create dialogue between the objects instead of displaying them in isolation.

"We're trying to make the objects work harder to tell the stories, now we can no longer count on visitors having first-hand memories of this history," he said. "Obviously there are none who were adults in the first world war, and even for the second world war, visitors would be very elderly, in their 80s or 90s."

The centrepiece of the new displays is a spectacular new first world war gallery. Many visitors, particularly younger ones, may mourn the loss of the old "trench experience", a vivid mock-up of trenches and dugouts, with life-size human figures and rats, smells and shell flashes.

Its tasteful replacement is a straight grey mud-textured passageway, with projected silhouettes of soldiers; though ominously overshadowed by a real Mark V first world war tank and Sopwith Camel overhead, it's no more frightening than an office foyer.

The new display begins with Britain as an imperial power, and ends with the muddled peace that sowed the seeds of future conflict. An interactive reveals the private thoughts of the world leaders portrayed in William Orpen's painting of the Versailles treaty – David Lloyd George described his French opposite number Georges Clemenceau as "a disagreeable and rather bad-tempered old savage".

Objects on display for the first time include a tunic button given as a souvenir by a German to a British soldier during the famous Christmas day truce. There is also a business card from one of the mademoiselles of Armentieres – or rather from Arras. The cards were handed out to soldiers by the keepers of one of the brothels tolerated by the authorities, and read "Ou irons nous ce soir? Voir ces dames Chez Madame Juliette." The consequence was that among the war's casualties were 150,000 British soldiers treated for venereal diseases.

For now the builders are gone, but they'll be back: more galleries, including major second world war and postwar displays, and a new ground-level entrance, will follow over the next few years.